Abstract: The National Matriculation English Test (NMET) employs a new item format: Text-based Grammatical Completion task. This paper reports a validation study on this new item format by means of a multi-dimensional discourse analysis with the intention to predict its potential washback effect on future EFL education in primary and middle schools in China. The case analysis of the 2014-item reveals multiple intentions of the test writers, and different kinds of competencies have been found to be elicited by the new item type, by which a new understanding of “grammar” is conveyed. The findings demonstrate that the implementation of the new test format will trigger a positive and facilitating washback effect on future primary and secondary EFL education in China. This research is significant not only in conducting a case analysis, but also in introducing a new method of text-based test method validation.