Laser cutting is one of the modern methods for cutting. In this noncontact method heat affected zone width and microstructure changes as a result and also sheet deformation are very low in comparison to other thermal methods and a fine cut is the result. In recent years usage of Laser for the cutting has grown greatly. This process can be automated using offline control systems applying on three-dimensional tables or six-axis robots. Improved accuracy, square edges and controlled heat input make laser cutting an alternative to other methods such as plasma and oxygen cutting. It is anticipated that the laser cutting because of improved cutting speed, no need for contacting tools and high flexibility will supersede other technologies. Also this method has great flexibility in cutting complex and simple patterns. On the other hand development of materials science presenting new materials with special properties has made the use of modern processing methods needful. Titanium and its alloys having some special properties like high strength to weight ratio, special strength against corrosion and good biocompatibility, have extensive use and application in the chemical, sport, medical and many other industries. Processes on titanium because of its low heat transfer conduction, low elastic modulus and high chemical reaction has challenges. Most famous use of laser is in cutting. Laser material cutting process starts with the metal melting by the laser beam and then the molten material will be removed by the assisting gas. In this research the effect of process parameters on HAZ and kerf width of Ti-CP have been investigated. The laser type was continuous wave CO 2 laser and selected parameters were laser power, cutting speed, assisting gas type and stand-off distance. In order to simultaneously study affective parameters, a L 16 orthogonal array is used. The samples were characterized with optical microscopy and microhardness tests. The samples were cut, polished and etched for metallography study. The results of hardness study showed that the hardness of HAZ near the base metal was reduced than the base metal. It can be attributed to the increase in grain size due to the low thermal conductivity of titanium and so heat imprisonment. On the other hand the hardness in the HAZ near the cut kerf was increased than the base metal. This can be attributed to martensite phase formation with high density due to rapid quenching. The quality criteria values were obtained using microscopic evaluation. Analysis of variance indicated that significant parameters on kerf and HAZ width were power with p-value of 0.015 and cutting speed with p-value of 0.045. These can be attributed to energy raise in the root of the laser beam by increasing the power and reduction of beam root contact to the besides of cut edges by increasing the speed. Also gas type tends to significant on the HAZ width. While simultaneously reducing HAZ and kerf width is considered, again cutting speed is the significant parameter and gas type and power tend to be significant. How the causes and effects of each parameter on the quality criteria changes have been described in the discussion section. Laser cutting of very thin CP titanium, using of continuous wave CO 2 laser, simultaneously investigation of parameters, individually and simultaneously investigation of quality criteria, use of gas mixture for cutting and wide range of parameters changes, are some attributes of this study. Keywords: Continuous Wave CO 2 laser, Cutting, Heat Affected Zone, Kerf width, Hardness.