Well drilling and well completion engineering in the fields such as unconventional oil and gas, hot dry rock, ultra deep well and so on have proposed urgent demands for the timeliness and accuracy of rock mechanics services, based on the rock physical or rock mechanical parameter of rock skeleton compositions such as mineral and kerogen usually is a constant, we study the rock mechanics parameters calculating methods through the rock composition surface logging technology which has such advantages as low cost, low risk , high timeliness,and high sampling rate, take the rock mechanics parameters calculation methods of dipole array acoustic well logging do forward modeling to determine the feasibility of rock mechanics parameters calculation through mineral components, and then take the mineral elements to construct the rock mechanics parameters directly, and these two methods are compared. As for 653 complex lithology data points, the average relative errors of young"s elastic modulus and poisson"s ratio calculated by forward modeling method are respectively 16.3% and 9.8%, the average relative errors of young"s modulus and poisson"s ratio calculated by direct method are respectively 10.0% and 6.8%. The results show that the rock mechanics parameters directly constructed by the elements have higher precision and better application effect in the area of relatively simple lithology.