Nonlinear distortion of CDMA optical module has severely affected the whole system performance in a communication system, for the problem, by the use of IP3(the third-order Intercept point) and IM3(third-order intermodulation signal) parameters as an index of measuring CDMA optical module nonlinear distortion, and distortion properties of optical modules is analyzed in detail from two aspects including lasers and amplifiers. On this basis, basic methods to improve the CDMA module distortion are discussed preliminarily, such a series of methods as changes to module internal laser bias currents, amplifier bias currents and peripheral matching circuits, and etc. The experimental results demonstrate that the proposed method is effective, which can improve the system distortion index in a certain degree, by watching influence on IP3 and IM3 parameters when condition changes. At present, the research for such distortion characteristics generally concentrated on the electrics, less on the optical devices combined with electrical devices at home and abroad. The method has certain significance and value for actual commercial optical module products.