Skill test was proposed in the extension of Knowledge Space Theory, but it gave nothing about the process of skill test. This paper defines question function, skill function, skill state function, and completes the mapping of knowledge structure onto skill structure. It also proposes a concrete process of skill adaptive test and gets the skill level of the testees. Furthermore, it introduces neighbor and boundary of knowledge state and optimizes a key process about selecting strategy in adaptive test, which helps tests to adapt to testees in knowledge.