Chlorophyll content non-contact spectral measurement has advantages of large measurement range,easy realization of automatic detection,etc.It is of great significance for implementing precision agriculture and building the intelligent monitoring system in the cultivate room.However,interference factors such as leaf structures,light scattering effect caused by leaf rough surface,and environment light will increase the difficulty of quantitative analysis.In this paper,a nonlinear modeling method which combines isometric mapping（ISOMAP）with partial least squares（PLS）is applied to non-contact measurement of plant chlorophyll content.It effectively improves the predictive accuracy.Compared with Wavelength Reference and Single PLS modeling methods,the predictive accuracy of ISOMAP-PLS model increases by 56.3%,34.4% respectively.The experiment results indicate that the ISOMAP algorithm can reduce modeling complexity and improve predictive accuracy at the same time.It is concluded that it is feasible to apply ISOMAP algorithm to chlorophyll content non-contact measurement.It lays the foundation for realizing non-contact measurement for variety of plant biochemical parameters,and for the development of the corresponding instruments in future.