It was analyzed that correlation between the transformed spectrum value and leaf nitrogen content,further more it was researched that retrieval precision for the nitrogen content with different form spectrum variables in 550nm and 680nm wave band by carrying on 6 kind of transformations to the corn leaf spectrum data.The results showed that differential form(D(R),D(Log(R))and D(N(R))) could significantly change the correlation between the nitrogen content and the spectrum value,and the normalized form(N(R))was next and the last was logarithm form(R and Log(R),N(R)and log(N(R))).In addition,determined coefficient of regression model was larger and the model precision was higher correspondingly with better correlation between different form spectrum variables and nitrogen content.In this study,the normalized logarithm form(log(N(R))) parameter of spectrum data could significantly improve the precision of regression model for retrieval nitrogen content in 550nm and 680nm wave band.