Abstract: For the slow operational speed problem of the Isomap algorithm in which the Floyd-Warshall algorithm is applied to finding shortest paths,an improved Isomap algorithm is proposed based on the sparseness of the adjacency graph. In the improved algorithm,the runtime for shortest paths is reduced by using Dijkstra's algorithm based on a Fibonacci heap,thus speeding up the Isomap operation. The experimental results on several data sets show that the improved version of Isomap is faster than the original one.