Vertical shaft spillways, especially the most common form namely morning-glory spillways have been widely used in a number of dam projects since the late 19th century around the world. Although a number of studies oriented to the shape of the inlet of shaft spillways including bell-mouth inlet, there are lack of research studies regarding to the inlet shape of these hydraulic structures. A brief review of researches in this field shows that most of the former studies have focused on the bell-mouth inlet to enhance the flow field thereby increasing the capacity using complementary structural elements such as; anti-vortex plates, trashracks etc. Thus the design of morning-glory spillways with bell-mouth shaped inlet has been experienced by design engineers. Improving the hydraulic performance of different types of spillways was a major objective of several studies, resulting in different forms of spillway crests such as; piano-key weirs and daisy-shaped inlets. Daisy-(marguerite) shaped inlets which are the subject of the present study have been applied in some dam projects. Applying this type of inlet with a specified form of intake structure, results in increasing the crest length of the spillway for a given vertical shaft spillway and effectively prevents the swirling flow and air-core vortices. Present study follows the former studies on daisy-(marguerite) shaped spillways which have been conducted in the department of Civil Engineering, Isfahan University of Technology. Former studies have been focused on the flow hydraulic characteristics through this type of spillways, by a radial inflow and the crest control flow regime. However, due to the lack of sufficient information about the hydraulic characteristics of flow around the marguerite-shaped spillways; in the case of swirling flow, the present study was performed. In respect to the asymmetry location of the vertical shaft spillways in the dam reservoirs, usually radial flow around the spillway is not a realized case; instead tangential flow behavior should be taken into account to analyze the hydraulic performance of these spillways. Experimental study was conducted in a hydraulic model of vertical shaft spillway equipped with the marguerite-shaped inlets. The flow discharges were ranged among crest control, orifice flow control and completely filled pipe flow on models of marguerite spillways with different geometries (including; the length, height and umber of blades). Accordingly the effects of spillways geometries on swirling flow, changing the flow regimes, the discharge coefficient and etc. have been quantified. Tests were performed in a circular cylinder of 2 meter in diameter and 1 m high. To create swirling flow condition, the flow was entered tangentially through a vertical inlet installed on the reservoir’s wall. Three-dimensional flow velocities were measured by an ADV installed over the reservoir with Frequency of 200Hz. The water free-surface profile was measured using piezometers installed under the reservoir floor. Results indicated that by increasing the length and height of the blades of a marguerite spillway, the swirling flow tangential velocity decreases, whereas the flow discharge increases. Also, increasing the length, height and number of blades results in the delay of air-core vortex formation, even in some geometries eliminates the air-core vortex. Dimensionless parameters were used to quantify the results and finally a correlation was derived for flow discharge coefficient of the marguerite spillways using statistical analysis. Keywords: vertical shaft spillway, morning glory, marguerite spillway, air-core vortex, hydraulic model, flow regime, swirling flow, discharge coefficient