This study was to develop a writing difficulties test of 1st grade to 3rd grade in the elementary school in Macao to help teachers to detect the students with writing difficulties, and further, teachers could design the curriculum for them. In order to develop the assessment, it was necessary to gather and analyze the literatures and the assessment about the writing diagnostic in Taiwan. Then the procedures are as follows: (1) Develop the papers. (2) Test for the pretest. (3) Conduct the formal-test. The results of the study were listed as follows. (1) According to the result of the reliability examination, the value of internal consistency was .943 (1st grade) 、.943(2ed grade)、.916(3rd grade As for the result of the validity examination, the content validity of this test was through 7 experts' review and judgment. Finally, there are some suggestions for the practical use and the future researches of the test.