Critical slip surface search is one of key problems in slope stability analysis. Present search methods include mathematic programming methods and brainpower search methods

which are based on the assumption of arc or arc-polyline slide style

and developed on basis of soil slope. It is not fit for rock slope. Critical slip field theory is based on residual thrust method and optimization theory. Useing new structure surface processing method

it can calculate the biggest residual thrust field

which is almost consistent with actual condition and easily search slip surface of respectively possible exits. Therefore

it can find the whole slope critical slip surface. First of all

using example of homogeneous material slope validates credibility of calculation result to be consistent with the result of shear strength reduction technique and the Spencer's precedure of limit equilibrium. Then

an example of open strip mine side slope is given to validate the practicability of this method.