  In this paper, we study a stochastic optimal control problem under degenerate
G-expectation. By using implied partition method, we show that the
approximation result for admissible controls still hold. Based on this result,
we prove that the value function is deterministic, and obtain the dynamic
programming principle. Furthermore, we prove that the value function is the
unique viscosity solution to the related HJB equation under degenerate case.
