Non-Orthogonal Multiple Access (NOMA) is a multiple access scheme that can increase channel capacity and spectral efficiency by using superposition coding (SC) on the transmitter and successive interference cancellation (SIC) to detect multiuser on the receiver. This paper investigates the effect of imperfect SIC and dynamic power allocation on NOMA channel capacity. Based on the simulation results, it is shown that the sum capacity of NOMA schemes in the imperfect SIC with dynamic power allocation is better than the sum capacity of orthogonal multiple access (OMA) schemes. The sum capacity of NOMA users with dynamic power allocation is better than fixed power allocation. In imperfect SIC, with a transmit power value of 3 0 dBm and the value of the residual interference level is 0.005, the channel capacity is 9.04 bps/Hz. While the residual interference level is 0.02, the channel capacity is 7.07 bps/Hz.