Currently, each research group that develops a new atomic parameter model typically has to implement it in MD from scratch. Such process is extremely tedious and requires highly skillful developers, thus can only be done by a few specialized research groups. Therefore, there is an essential barrier between building the model and validating it in real MD simulation, which limits the throughput of force field development. Meanwhile, it is noticed that some of the computational kernels (such as PME, pairwise interactions, minimization with respect to charges and dipoles, etc.) are quite common, but still need to be implemented repeatedly in different scenarios. It would be ideal if we can design the most commonly used modules in advance, and assemble or extend them at will when exploring new potential forms. Previously such modular force field development is not feasible due to the needs of force and virial tensor calculations: differentiating through different modules can be cubersome. The automatic differentiable DMFF package is designed to solve this problem. All commonly used molecular force field kernels are implemented with a user-friendly interface, which can be recombined easily to form new potentials.