The advantages of portfolios come from observing the student learning process and recording feedback. Students utilized their own learning portfolios to do learning assessment and self-correction. The research that has been done in Taiwan has shown that using a portfolio is effective in improving English speaking performances (ESP). The purpose of this study is to apply the portfolios to assess students' speaking performances. The researcher administered speaking evaluation forms and the PRCA-24 as the instruments. The PRCA-24 was used to assess students' communication apprehension and was analyzed by t-test. The major findings were summarized. The portfolios were expected to enhance students' ESP and intended to reduce students' communication apprehension through self-monitoring their ESP. Finally, this research can provide valuable perspectives on the use of portfolios and self-monitoring, and prompted the expansion and sustainability of English education system. (Contains 2 tables and 1 figure.)