Nowadays, reliability standards play a major role in planning and operation of distribution systems. This issue has been become more challenging in deregulated power systems. Reconfiguration is one of the operational activities in distribution systems which is done with different objectives such as power loss reduction, reliability improvement, load balancing and etc. This thesis presents a new method based on fuzzy implementation of harmony search algorithm in distribution network reconfiguration for reliability improvement and loss reduction. The fuzzy approach will guarantee an optimal compromise solution. The harmony search along with some modifications to match with reconfiguration problem is employed which enables the method to obtain the global optimum in most case studies. Cut set theory is used to evaluate the system reliability indices. Applying this analytical method results in shorter calculation time compared to Monte Carlo simulations. Reliability indices of distribution systems are introduced and calculated in various operational conditions. A backward-forward load flow is used to evaluate power loss and to satisfy bus voltage and line current limits. Radiality of the proposed configurations is ensured by graph theory. The proposed method was successfully implemented in standard test systems. Simulation results indicate the effectiveness of this method. High speed, makes this method ideal for online applications. Key Words Multi-objective Distribution System Reconfiguration, Reliability Improvement, Loss Reduction, Fuzzy Approach, Harmony Search Algorithm