The invention discloses a bottom-preserving net rack search modeling method based on mixed integer second-order cone planning. The method aims to solve the problems that an algorithm adopted in the prior art is low in calculation speed, uncertain in result and limited. The method comprises the following steps: S1, collecting information of a to-be-planned power transmission network, forming an initial power grid topological graph, and establishing a multi-objective optimization function; S2, establishing node active power and reactive power balance constraints on the basis of the power flow equation of the power system; S3, establishing model inequality constraints including a line voltage constraint, a system power flow constraint, a connectivity constraint, a unit output constraint and aline power constraint; S4, performing second-order cone optimization relaxation on the model, and converting the mixed integer nonlinear programming model into a mixed integer second-order cone model; and S5, solving the model to obtain a planning scheme. Through the mixed integer second-order cone programming, solving efficiency is high, robustness is good, and the result is determined. Searching speed and accuracy of the guaranteed net rack are improved.