Prof. Li has been long devoted himself to the study of underwater acoustic signal processing and sonar design and development. Based on his analysis of the features of acoustic propagation in shallow sea of our country, he innovatively applied the traditional methods and theories to solve the new problems related to underwater acoustic signal processing. His successful researches have made great contributions to national naval sonar equipment modernization. Moreover, Prof. Li was dedicated to the study of steady-state performance of self-adapting beam shaping, put forward the expression of beam directivity with the frequency domain optimal transmission function, presented the gain calculation method of testing feeble signal under the oceanic noise circumstance, revised the classic theory under the condition of unstable and uneven sound field and brought forward important basis for sonar design - a new expression of sonar equation. Furthermore, he created a new method of using the phase information of the sound signal to orientate the objects in the passive test condition.
Besides the practical research, Prof. Li also got great achievements in theoretical studies. In his 50 years' research life, he has published many academic papers and works, such as Study on self-adapting noise neutralizing filter and neutralizing capacity, Computer simulation technique in sonar design, Self-adapting array signal separation theories, Introduction to sonar signal processing, Computer graphics and so on.
For his hard work and fruitful research results, Prof. Li was elected to be the academician of Chinese Academy of Sciences in 1997. Also, he was granted CAS Key Science and Technology Progress Award of 1st grade in 1976, National Science Congress Award of 1st grade in 1978 and Science and Technology Progress Award in 1984.