Using practical vocabularies and phrases plays a prominent role in developing speaking skill. The current research was designed to analyze the effect of implementing panel discussion on speaking skill of Iranian intermediate EFL learners. It was carried out at Ghasedak language institute in Astara among 70 intermediate male learners with the age range of 16-24 through a quasi-experimental research. The participants were assigned into two groups. One experimental group and the other labeled as control group. First, the pretest was administered to each group. The test was taken from the book “American File”. At the end of 10 weeks, a posttest of speaking was given to both experimental and control group. Then learners’ accuracy in simple past, simple present and present perfect and their fluency in using practical vocabularies and phrases were assessed. Results showed that teaching speaking based on panel discussion through CLT had a significant effect on learners' speaking skill.