Objectives: Several factors, including pregnancy which is associated with physical, psychological, and hormonal changes, affect females and their sexual partners’ relation and function. This study aimed to investigate the effect of "permission, limited information, specific suggestions, intensive therapy" (PLISSIT)-based sexual counseling on the sexual function of pregnant women. Materials and Methods: The present randomized controlled trial was performed on 70 pregnant women who had a sexual function score of less than the cut-off point within a gestation period of 16-20 weeks. The participants were randomly divided into intervention and control groups by the blocking method. The intervention group received individual counseling based on the PLISSIT model by a well-trained midwife while the control group only received the usual care for pregnancy. The primary outcome measures were the total score of female sexual function four weeks after the intervention. Finally, the data were collected using a questionnaire of personal and midwifery information, as well as the female sexual function index in previous stages and four weeks after the intervention. All analyses were based on the intention to treat the approach. Results: There was a significant difference between the mean total score of sexual function (adjusted mean difference: 9.07; 95% CI: 7.24 to 10.90) and all the sub-scales that intervention and control groups adjusted for baseline scores four weeks after the intervention (P<0.05). Consultation significantly reduced the frequency of sexual dysfunction and there was a significant difference between the 2 groups in this regard (P<0.001). Conclusions: Given the effect of sexual counseling on the improvement of sexual function of pregnant women based on the PLISSIT model, this approach is recommended during pregnancy.