To improve the machining efficiency and surface accuracy of curved parts, a new approach called Weak-Chemical-Coordinated-Thickening Polishing (WCCTP) concept is proposed for ultraprecision manufacturing of the key work surfaces of a spherical plain bearing in this paper. A specific WCCTP slurry (WCCTPs) is successfully prepared to achieve two capabilities: one is the shear-thickening rheology to form flowing abrasive-polymer-clusters with flexible shearing material removal with tribo-microcutting, the other is weak chemical-coordinated interaction to soften the worksurface with enhancing surface accuracy. High viscosity easily produces an effect on the excessive aggregation of abrasive-polymer-clusters, resulting in blockage called a jamming phenomenon. The peaks of each surface in the contacting zone are polished from the work substrate during these shearing actions of the “flowing abrasive tool”. In view of the principle of liquid thickening dynamics and chemical mechanism, a predictive mathematical model of material processing in WCCTP is established to guide the actual production. Under the condition of the verification experiment, the maximum deviation of this predicting equation can be controlled at about 8.03%, which demonstrates the effectiveness of our proposed WCCTP process. The effects of shearing velocity, abrasive concentration, abrasive size, weak chemical-coordinated interaction, polishing temperature, and gap depth are investigated in detail to illustrate the application of WCCTP on machining efficiency and surface accuracy. Moreover, the optimization applied to the actual experiment result indicates that our proposed WCCTP approach can implement the ultraprecision polishing for the spherical plain bearing of Sϕ 56.6 mm, and develop an ultra-smooth mirror with the roughness of Ra 25 nm, the roundness error of 4.0 μm, and high shape accuracy (=PV 1.16 μm). This work indicates that the WCCTP approach is a progressing ultraprecision machining on spherical curved 9Cr18 parts.