Abstract: A manipulator is designed for the problem of conical surface mounting and its working quality is evaluated. Firstly, the configuration of the manipulator is designed, the working principle is clarified and the spatial degree of freedom is calculated by using the modified GK formula. Secondly, the quality evaluation method of mounting work is proposed. The concept of surface displacement is proposed to evaluate the degree of fit. The surface displacements in the two directions of circumference and generatrix are collected respectively and the range and variance are calculated. The range and variance in the two directions are averaged and the reciprocals are weighted by 0.99 and 0.01 to obtain the original mounting quality evaluation parameter S value. Thirdly, the orthogonal test is designed with the mounting height and mounting strength as variables, and the S value is collected and calculated to obtain the F value of the influence degree of the variable on the mounting quality. Fourthly, the effectiveness of the evaluation method proposed in this paper is verified by the plane paving test which does not involve the change of mounting height. Finally, this method is applied to the conical surface. The results show that any single increase in the mounting strength and mounting height can improve the mounting quality. Under the combined action of the two factors, the corresponding F value of the mounting strength is 10.32, and the corresponding F value of the mounting height is 3.50.