The calculation method of the tight force of the spring collet of precision machine tool spindle was studied. Its reliability analysis model was established, and the reliability of the tight force of the spring collet of precision machine tool spindle was calculated. Moreover, the nonlinear finite element model of the whole spring collet tight device was established, and it was verified through comparing with the theoretical results. From the results of FEA, the contact deformation law between clamping surfaces was obtained. It provides method and basis for design and performance analysis of spring collet of precision machine tool spindle.