The present invention provides a pharmaceutical composition comprising mesenchymal stem cells, a hyaluronan and a pharmaceutically acceptable carrier. The pharmaceutical composition is used for the treatment of the joint disease. The mesenchymal stem cells in the composition are at least one selected from the group consisting of infra-patellar fat pad stromal cells, bone marrow stem cells, Wharton's jelly stem cells and adipose derived stem cells. The concentration of the hyaluronan is in a range from 25% (v/v) to 75% (v/v). The present invention further provides a method for treating a joint disease, comprising a step of administrating a composition containing mesenchymal stem cells, a hyaluronan and a pharmaceutically acceptable carrier to an injured joint tissue of a subject.