Using frequency and ratio measures as indicators of English Oral Performance Accuracy, the present study explored the relationship between oral accuracy measures and oral performance quality. Through an induction task a corpus of 61 speech samples by English majors was built. Results based on the analysis of this corpus indicate that 1) when the external factors such as task condition, duration and attitude of the subjects are controlled, the number of error-free clauses, number of error-free T-units and the ratio of correct verb forms are effective measurement tools that can affect scores of oral test; 2) The total number of verb phrases, T-units and the ratio of correct verbs verb forms are the most precise predictors of the quality of oral performance; 3) Number of error-free clauses, number of error-free T-units and the ratio of correct verb forms are especially distinctive. The implication for Spoken English Teaching is to cultivate students the capacity of producing longer stretch of discourse, to guide students to pay attention to the match between form and meaning based on verbs and their collocation, and to improve the accuracy of students’ language use.