In order to reduce the pressure drop increase caused by self-rotating plastic twisted-strips in heat transfer tubes of vacuum condensers in thermal power plant, the twisted strips structure is optimized. There are holes distributed in twisted strip uniformly. The holes diameter and interval are optimized through experimental research. The results show that when holes diameter is less than 6mm, holes can reduce the pressure drop increase at low flow velocity while the pressure drop with holes is greater than that without holes at high flow velocity. The holes diameter is 4~5mm when the pressure drop is the lowest. The pressure drop with holes is always larger than that without holes when holes diameter is more than 6mm. The pressure drop will increase as holes interval decreases at high flow velocity, while it will reduce at low flow velocity.