For studying the influence on low voltage ride through characteristics of wind power generating unit caused by replacement of generators and based on a type of 1.5MW wind turbine from GDUPC, the paper demonstrates feasibility of the replacement and carrys out a quantitative research on the influence that the replacement results in parameter variation of generator, according to theoretical analysis of transient and steady operation for the unit. In addition, a mathematical model for unit is programmed in Matlab Simulink which has been calibrated and acknowledged by third-party certification. Acquired from inputting equivalent circuit parameters of generators into the model and Simulating, Some technical indicators that reflect working status of wind power generating unit could be utilized for comparative analysis that makes a qualitative conclusion. As reference, the paper could provide theoretical guide for practical engineering application and improve the present method for LVRT detection.