This paper studies how a monopoly firm produces and prices its product under the influence of stochastic market environment and reference price. We formulate it as a stochastic control problem, whose aim is to maximize the net profit. The evolution of inventory system and reference price is given by a two-dimensional controlled stochastic differential equation, while the stochastic market environment is captured by a continuous time Markov chain. Firstly, by using the dynamic program principle and the viscosity solution method, we show that the value function is the unique viscosity solution to the associated optimization equation, also known as the Hamilton-Jacobi-Bellman (HJB) equation. Since the HJB equation is usually not easy to solve explicitly, we figure out the finite difference approximation scheme to numerically approximate the value function. Convergence analysis is also given. Finally, through numerical examples and sensitivity analysis, our theoretical research results are intuitively demonstrated, which provides a quantitative reference for inventory management in practice.