The dynamic and open environment has its own unique characteristics，and the search aIgorithms that want to survive in this environment and handle the real time Droblems must deal with these characteristics．What is the requirement to such search algorithms? This paper gives out some hints to the answer．It describes a search algorithm suited for dynamic environment，leap algorithm，which has realized some ideas in the anal—vsis．The algorithm can run more efficiently than a famous real time algorithm RTA*，and the experiment data support this point．