Mobile edge computing (MEC) and reconfigurable intelligent surface (RIS) are two highly promising key technologies in future wireless communications, dedicated to enhancing the computational capabilities of communication systems and optimizing channel transmission performance, respectively. To address the problem of minimizing the task delay in a multi-user non-orthogonal multiple access (NOMA)-MEC network , RIS is deployed to improve the communication performance, enabling multiple users to offload tasks simultaneously through the same frequency band. We jointly optimize the RIS phase shift, offloading power, beamforming, and distribution factors, and design an equalizer at the receiving end. Since the problem is non-convex, the semidefinite relaxation (SDR) algorithm is used to optimize the phase shift of RIS, the successive convex approximation (SCA) algorithm is used for the power and allocation factors, the equalizer is designed by the minimum mean square error (MMSE) criterion, and the delay is minimized by the alternating optimization.