The present study aims to investigate the factors affecting the choice of aspectual verbs “begin” or “start”, the factors affecting the choice of their complements, and the possible relation between the two choices in English Academic Writing. With the VARBRUL approach, a model has been found to account for these questions. The choice of “begin” or “start” is affected by the preceding syntactic tags, the choice of the complement is thus controlled by the choice of the aspectual verb, and both the two choices are affected by a social factor. In addition, the model of the VARBRUL analysis can be further applied to Natural Language Processing and English Academic Writing Teaching or Assistance, so a VARBRUL analysis is thus very economic. Other findings show the comparison of the model prediction among Logistic Regression, Decision-Tree-based Logistic Regression and Neural Network with linguistic data.