A debris avoidance guidance method wasis proposed to utilize the detection information from the space debris situational awareness system to actively avoid space debris and achieve high-precision orbital insertion. An optimal guidance problem for launch vehicle ascent debris avoidance was formulated. The motion of space debris was modeled using Kepler dynamics with state uncertainties, and a debris threat radius was defined based on state uncertainties. A state uncertainty propagation predictor based on polynomial chaos expansion was designed. Taking the measurement errors of the current position and velocity vectors of debris as initial values, the time-varying threat radius of the debris was obtained by predicting the uncertainty propagation of the debris state errors. Through derivation of the optimal guidance form for debris avoidance, a two-stage linear tangent guidance law for single debris avoidance and a guidance strategy for multiple debris avoidance were proposed. Simulation results show that the proposed debris avoidance guidance method can achieve the active avoidance for multiple debris and satisfy the orbital insertion accuracy.