To alleviate the issues of high complexity and poor scalability in the processing of keyword-aware optimal route query algorithms for large scale graph or multiple query keywords, an effective algorithm was proposed based on the scheme of keyword sequence route generating. The algorithm satisfied the coverage of query keywords first, and took a path expansion inspired by the keyword coverage property rather than aimless adjacent edge expansion to efficiently construct candidate paths. With the aid of a scaling method and ineffective route pruning, the search space was reduced into a polynomial order from an original factorial order, which further reduced the complexity and enhanced the scalability. Experiments conducted over four gragh datasets verified the accuracy and improvement in efficiency and scalability of the proposed algorithm.