This paper reports a study investigating business English teachers' belief about online assessment using Q methodology. To address the common practice that teachers had to conduct online assessment during COVID-19 period and with performance assessment as theoretical foundation, this paper studied 22 Chinese business English teachers' belief when they had to do assessment in online context. With data analysis from Q-methodology and complementary interviews, the findings of this study showed a shared configuration among the business English teachers in three factors: strong belief in performance assessment for business English courses; belief in supportive role of ICT; and belief in assessment as an ongoing process. The three factors were further interpreted from systematic approach of assessment and the role of ICT in online teaching. This study will be of significance to help teachers improve the quality of online assessment and raise their awareness of effective use ICT in online teaching.