Jets are excellent probes to study the evolution of protostars since they carry along the fossil information on the beginning of star formation. Recent observations have shown that X-ray emission and high energy particles exist in Young Stellar Objects (YSOs) jets and their knots. However, the mechanisms for plasma heating and particle acceleration are not clearly verified. In this presentation, we will introduce our recent experimental results on the reproduction of knots in YSO jets with intense lasers in laboratory. X-ray emission and electron energy spectra are both obtained. We have also proposed a new model to explain the shock formation and the heating of the plasma.