It is a crucial problem in the field of high energy lasers to control Β integral (i.e. self-focusing) and to restrain it effectively. As conventional control techniques of Β integral (e.g. spatial filtering) nonetheless are far from solving the problem, novel techniques need to be developed. Based on nonlinear frequency doubling the cascaded second order nonlinearity, virtually equivalent to the third order nonlinearity, has a controllable sign (allowing of negative values), variable values that can be veiy large, and can eliminate two-photon absorption. The cascade nonlinearity provides a new degree of freedom for short-pulse sources to produce serviceable nonlinear phase shifts. The preliminary experiments show that using these negative phase shifts can to a certain extent compensate for the cumulative Β integral due to the nonlinear propagation of high power laser (pulse) beams.