Wireless sensor networks（WSNs）have some special characteristics such as placing expediently

self-organizing and strong mobility.In order to guarantee the safety in production

the nodes of the network can be put on the coal mine working face to provide real-time monitoring the condition of the large-scale equipment and the environment parameter.The coverage algorithms for variable sensing area is proposed based on the environment mentioned above

and the algorithm is simulated the support of B-spline theory and Matlab.The result shows that the degree of coverage increases as the communication radius increases;reasonable choice of the first cluster head will achieve high degree of coverage;appropriate node density can also extend the life of the network except covering the sensing area effectively.