This Study uses descriptive research as the method of collecting data. The main purpose of this study is to know the weaknesses and the strengths of students.
In this study, the writer uses simple random sampling as the method of collecting the data which used all students of XI AP 1 at SMKN 1 Demak. The writer gave three kinds of test. They are reading test, speaking test, and writing test. Then from the result of those tests, the writer found the students’ weaknesses and strengths by using Microsoft Excel.
The result of this study showed that the lowest ability of reading skill is material of suggestion and offering and the highest material is procedure text. For writing skill, there are two materials which are the lowest result. They are suggestion and offering and hope and wish. The highest material that students master :simple letter and formal invitation. The last is speaking skill. In this skill, there are not many significance results. It shows that the lowest materials are suggestion and offering and formal invitation. The highest materials are all materials except two materials above.

Keywords: analyzing, learning need, diagnostic test