Abstract：During drilling well，keeping wellbore stability is very important for drilling normally. More and more importance is attracted to the wellbore stability evaluation while drilling，because it can reveal the wellbore status real-time. And rock mechanical parameters are essential to the wellbore stability evaluation，so developing the model of rock mechanical parameters evaluation while drilling becomes core of the work. On the basis of the mixture theory，the influence factors of rock physical properties are entirely recognized，and the important influences of microstructure on rock physical properties，especially on mechanics，acoustic velocity and resistivity property，are analyzed. Statistical analysis of field logging data is progressed，consequently a linear relationship between rock acoustic velocity and ratio of logarithmic resistivity at different detecting depth is obtained. On this basis，the model of rock mechanical parameters evaluation with LWD(logging while drilling) formation resistivity data is developed. The model is applied in evaluation of rock mechanics and wellbore stability in some areas，and it wins a good effect.
