The experiments of vapor cloud explosion were carried out respectively in which the hemispherical strip barrier and the global pouched barrier were set. The pressure-time curve was recorded by system consisted of pressure transducer,A/D card and computer with less than one millisecond. A program was designed to calculate the explosion impulse of observed spot on the basis of pressure-time curve,and the effects of the characteristic parameters of barriers on the explosion impulse were studied. The experimental results show that the explosion impulse increases with interspaced ratio,vapor cloud radius,and barrier radius. The relationship between impulse and distance in the hemispherical vapor cloud is approximate cosine. Moreover,a fitting equation to calculate explosion impulse of hemispherical vapor clouds was proposed by applying multi-energy model.