We systematically investigate a strain of self-assembled InAs/GaAs quantum dots (QDs) for the case of growth on a (001) substrate. The dependence of the biaxial and hydrostatic components of the strain on the quantum dot aspect ratio is studied using a finite element method. The dependence of the carrier's confining potentials is then calculated in the framework of eight-band kp theory. The shifts of the energy level in three shapes of QDs are investigated. By comparing the results, the influence of the strain on the QDs are given.