In this letter, a new array synthesis method called weighted alternating projection and proximal splitting is proposed, which combines the alternating projection (AP) and constrained weighted least mean squares (CWLMS). Under the framework of AP, we first study the projectors over the pattern and excitation constraints in detail. Especially for the projector over excitation constraints, it is designed as the solution to a CWLMS optimization. Then an effective proximal splitting method is developed to solve the CWLMS optimization using proximity operator theory. To demonstrate the performance of proposed method, several planar synthesis examples with embedded element patterns are presented and the results show that the proposed method has better performance.