The scale and complexity of search space are important factors to decide the solving difficulty of an optimization problem. The information of solution space may lead searching to optimal solutions. Based on the known space structure of job shop scheduling problem, a space contracting and decomposing algorithm is proposed. This algorithm makes use of the good solutions found by searching algorithms, contracts the search space and decomposes it into one or several optimal regions combined with the concept of Backbone of combinatorial optimization solutions. And optimization of small-scale problems is carried out in optimal regions. Statistical analysis is not necessary before or through solving in this algorithm, and solution information is used to estimate the landscape of search space, which enhances the speed and solution quality. The experiments results testify the efficiency of this new algorithm.