The coherent optical control of exciton quantum states in semiconductor quantum dots (SQDs) is essential for quantum information and quantum computing. The decoherence physical mechanisms of quantum dots (QDs) can be acquired through analyzing the influence of Rabi oscillation,which provides the theoretic support on all-optical coherent control of multilevel excitonic system. Self-assembled InGaAs QDs is excited by the linear polarized pulse field,the exciton dynamics equations of a three-level V-type system with single pulse are deduced from the master equations of the populations and the Bloch vectors. Based on the exciton dynamics equations,the effect of initial conditions and pure dephasing on Rabi oscillation are discussed. The results show that the amplitude and frequency of Rabi oscillation on exciton can be manipulated by adjusting initial conditions and the polarization angle of excitation field,and the simple intensity dependent damping factor of pure dephasing can well describe the decoherence properties of the V-type three-level system,so that relevant calculation is simplified.