Virtual instrument (VI) is an integration of the most recent PC technology, advanced testing technique and strong software package, and the VI system development is the modern technology trend in the automatic test and fault diagnosis domain, etc. Firstly, the intelligent fault diagnostic flat for the shipboard equipment is developed, applied the VI technology, wavelet neural network and database, in order to update entirely the testing means. Secondly, the modularization and universalization are proposed in its database-based design concept, realized the software and hardware design, and it broke through conventional check diagnosis patterns, resolved difficult to overcome problems brought on adopting existing conventional fashions examined and repaired the shipboard equipment, greatly shortened the maintenance cycle. Lastly, it was proved by experiments that the flat system has merits, such as high testing precision, strong flexibility and reliability and extensibility, and economical practicability. Also it can reduce the application development cycle and cost, and is of some values for developing the other fault diagnostic instrument.