This study investigates the effectiveness of using Google Translate as a translingual CALL tool in English as a Foreign Language (EFL) writing, keyed to the perceptions of both more highly proficient Chinese English major university students and less-proficient non-English majors. After watching a 5-minute passage from a movie, each cohort of students was asked to write an extemporaneous reflective essay. Students first wrote a text in Chinese, then composed a corresponding text in English, submitted their Chinese text to Google Translate (GT), compared the translated English GT text with their own self-written (SW) text, and finally revised their self-written English (RSW) text by referring to their GT text. Student perceptions of the activity were elicited by a questionnaire. Two types of online computational assessments evaluated students' writing performance for all the SW, GT and RSW versions. Results indicate that GT texts showed significantly better writing performance in delivering more enriched content, using more advanced vocabulary and making fewer spelling and grammatical errors than the SW texts. RSW texts showed a significant improvement over SW versions, especially for the non-English major students. Students using Google Translate as a revision tool displayed better L2 performance in written language and content than in their self-writing, and especially non-English major students showed significantly more positive attitudes towards the use of Google Translate than English major students.