In order to improve the performance of screw compressor, it is important to know, understand, and analysis the different geometrical as well as operating parameters on the compressor performance. Consequently, the present study is concerned with obtaining the characteristics of twin-screw compressor by using a simulation code named SCORPATH. Explanation of the code is presented and discussed. A parametric study was performed to determine the effect of the geometrical and the operating parameters on the performance of screw compressor. The study revealed that the geometrical parameters: clearance gap, number of lobes in the rotors, rotor relative length, and screw wrap angle, have significant effect on the performance of the screw compressor. In addition, built in volume ratio, tip speed, suction and discharge pressures, are the operating parameters which have a great effect on the performance of the twin-screw compressor.