Neural network mapping algorithm is an important research content in the field of neural network virtual implementation. The efficiency of the algorithm affects the virtual implementation of neural network. In this paper,the nature of neural network mapping，the neural network topology and the neurocomputing process have been analysised at first. Based on thorovgh consideration of load-balance and communication-cost，the thesis gives a general-purpose efficient neural network mapping algorithm. introducing the idea of timestep. Finally, the experimenting results of neural networks with different topologies are presented，which proves the generality and efficiency of the algorithm.