There is close connection between vibration signal and combustion status before peak pressure. Comparison was carried out among the vibration acceleration signal, cylinder pressure, rate of pressure rise and pressure rise acceleration before peak pressure. Based on the similar trend waveform, a novel method using inflection of vibration acceleration to estimate combustion process feature points was proposed. Contrast was also carried out among cylinder pressure, rate of pressure rise, time domain waveform and frequency component amplitude of vibration acceleration and pressure rise acceleration. Results showed that the maximum time domain fluctuation and frequency component amplitude of vibration acceleration are closely related with combustion status and the information can be used as characteristic parameters to reflect combustion status. Experiments were carried out and the result verified that the characteristic parameters were feasible.