Learning basketball tactic via virtual reality environment requires real-time feedback to improve the realism and interactivity. For example, the virtual defender should move immediately according to the player's movement. In this paper, we proposed an autoregressive generative model for basketball defensive trajectory generation. To learn the continuous Gaussian distribution of player position, we adopt a differentiable sampling process to sample the candidate location with a standard deviation loss, which can preserve the diversity of the trajectories. Furthermore, we design several additional loss functions based on the domain knowledge of basketball to make the generated trajectories match the real situation in basketball games. The experimental results show that the proposed method can achieve better performance than previous works in terms of different evaluation metrics.