Abstract: In order to solve problems of weak basis of student and less teaching hours but more teaching content in electrotechnics course teaching, random access instruction strategy based on cognitive flexibility theory was adopted in the electrotechnics course teaching. On the one hand, concept and related case are characterized with hypertext structure of multidimensional and nonlinear cross-shape, so as to raise multiple representations ability for cognition of student and enhance transfer and coverage of knowledge. On the other hand, mnemonic method which is applicable to low-level learning is attached to multi-knowledge representation, so as to form star-shape, which has strong adaptability for the electrotechnics course teaching at present stage.