Optical properties in injection molded plastic lenses for mobile phone camera have been simulated using commercial program, 3D TIMON. Four plastic lenses are being used in mobile phone camera. The quality of photographs taken by mobile phone camera is strongly depends upon optical characteristics of lenses. The variety of optical properties has been investigated according to the injection conditions through the computer simulation. Consequently optimal injection conditions for four lenses have been determined and simulation results of birefringence have been compared with experiments.