A new imaging method, Deramp-nonlinear extended chirp scaling (Deramp-NECS) algorithm, was proposed for high resolution squint missile-borne hybrid Synthetic aperture radar (SAR) in high speed dive trajectory. The hybridization degree of missile-borne hybrid SAR in dive trajectory was redefined. Then the equivalent range model and the expressions of echo signals were presented. By analyzing the missile-borne hybrid SAR echo signal, it was presented that the cubic-order phase item existed and had to be compensated. Deramp-NECS algorithm was put forward to implement the missile-borne hybrid SAR imaging. It firstly solves the azimuth spectrum aliasing using deramp processing with constant Doppler frequency modulation rate to realize the coarse focusing in azimuth. Then the improved CS principle introducing non-linear frequency compensation is used to get the fine focusing in range, while the azimuth errors caused by deramp processing are also compensated to realize the fine focusing in azimuth. Finally, computer simulation is employed to validate the availability.