Kinematics analysis is the basis of kinematics performance evaluation and structure size optimization of parallel mechanism. The existing kinematics analysis methods of parallel robots have the problem of separating geometric modeling from geometric calculation. A method for inverse kinematics analysis of parallel robots was proposed by taking advantage of conformal geometric algebra (CGA), which integrated geometric representation and calculation. Firstly, the rigid body transformation of any point on the moving platform was realized by the geometric product under the framework of conformal geometry algebra, and then the conformal geometric expression of any point in the process of motion was obtained. Then the kinematic equation of the mechanism was established by using the inner product operation in combination with the dimension and geometry constraints of the mechanism. Finally, according to the kinematics equation, the inverse kinematics was calculated and the velocity was analyzed. A 3-RPS parallel robot of three degrees of freedom and a 6-UPS parallel robot of six degrees of freedom were taken as examples to verify the correctness of the proposed method, and the results of inverse kinematics were compared with those obtained by simulation software. This method combined the geometric objects such as space vector and rotation representation with the calculation methods such as matrix multiplication and vector outer product, so that the spatial geometry problems of parallel mechanism were handled in a unified algebraic system, so the analysis process was geometrically intuitive, and the analysis and calculation process of inverse kinematics were simplified.