Abstract: Nitrogen is one of the necessary nutrient elements for crop growth and yield formation. The paper interpretes the study background and need on technique of crop nitrogen diagnosis in agricultural production, introduces development course and trends of crop nitrogen monitoring and diagnosis in crop production, and summarizes domestic and overseas advances of crop nitrogen diagnosis technique. The non-destructive, rapid and accurate monitoring and diagnosis of crop nitrogen nutrition is of significance, and which improves sustainable development of agricultural production and environment protection．