Provided is a portable crop growth information monitor based on an active light source. The monitor is characterized by comprising a light source system, a spectrum signal acquisition system and a main unit system. The front end of the light source system is connected with the main unit system, the rear end of the light source system is connected with the spectrum signal acquisition system, the rear end of the spectrum signal acquisition system is connected with the main unit system, and the rear end of the main unit system is connected with the light source system. The monitor can simultaneously and comprehensively monitor and diagnose various physiology and zoology information including chlorophyll content of crops, a normalized difference vegetation index (NDVI), a leaf area index, leaf dry weight, nitrogen content, nitrogen accumulation amount, a net photosynthetic rate, a transpiration rate, leaf temperatures and the like, and has functions of data acquisition, analysis, display, storage, checking and display. By means of application of built-in electronic information techniques, the system structure is simplified, and the monitor has the advantages of being convenient to carry and low in power consumption and the like.