Abstract: Combined with on site practices,the mechanics analysis of the perforating combined well testing string is carried out.The effect of high pressure and the vibration of perforating gun on the string is analyzed more emphatically.It is demonstrated that the high pressure produced in the sealing interval is the main factor that causes the string vibration at the instant of detonating,and the vibration absorbing method of the string is put forward.The high pressure is indicated as the main factor causing damage of the pressure gauge.Based on which,the proper string structure,and protecting devices of the downhole instrument are designed.The success rate of perforating combined well testing operations is increased.