Abstract: The present study was conducted to seek the diagnoses of bamboo nutrient state so as to guide its fertilization.Research contents included methods of tissue sampling for foliage analysis,and evaluation of nutrient status of field bamboo fertilizer experiments by the traditional critical value method and DRIS method which has been developed recently.The results are as follows:1.Tissue samples used for foliage diagnoses should be collected during the middle of shooting stage,and from the median branches of crown with 2-year age bamboo trees.In order to represent the nutrient content of plants,5 single bamboos,at least,were needed to be collected for a mean sample.2.Critical value standards were affected by the structure of standing bamboos.As standing bamboos had more than 250 culms per mu (1/15 ha),N,P critical values were respectively 2.6% and 0.13%; optimum values were 2.8% and 0.16%.With sparse standing bamboo trees,or of which top parts of crown were cut off,N critical and optimum values appeared to be a little high up to 2.9% and 3.1%.The output responses of new culms,accumulating in 3 years,agreed with N,P concentration levels.3.DRIS reference values were obtained from the high-yield population of fertilizer experiments (yield 3500kg per mu).DRIS method was evaluated utilizing 4 data sets of N,P,K,Si.In general,where the critical value method made a diagnosis,it agreed with DRIS.DRIS had advantage over the critical value method to assess the status of nutrient balance of plant and nutrient order of requirement.But incorrect diagnoses might occur as nutrients were relative insufficencies or excesses.Considering the variety of forest sites,both the above methods should be recommended together for nutrient diagnoses in bamboo forests.