Abstract: The article have studied the characteristics of ultrasonic plastic soldering of PC materials with energy rib.Energy rib can reduce high frequency electric energy density needed for soldering,or under the condition of the same high frequency electric power,soldering area of using energy rib is several times by plane soldering.After melted,the increasing height of unit area H on soldering surface,resulted from using rib,affects soldering strength F considerably.By experiments,the article corrects calculating method of high frequency electric energy density and electric power,and give correcting factor k₁ that ensures theoretical calculating results conform to practice.This confusion will give impetus to the moreextensive applications of ultrasonic plastic soldering technology.