Discrimination of cancer cells/tissues from normal ones is of critical importance for early diagnosis and treatment of cancers.Herein, we present anew strategy for high-contrast fluorescence diagnosis of cancer cells/tissues based on b-Lapachone (b-Lap,a na nticancer agent) triggered ROS (reactive oxygen species) amplification specific in cancer cells/tissues.W ith the strategy,awide range of cancer cells/ tissues,i ncluding surgical tissue specimens harvested from patients,w ere distinguished from normal ones by using ac ombination of b-Lap and aS i-rhodamine-based NIR fluorescent ROS probe PSiR3 developed in this work with average tumor-to-normal (T/N) ratios up to 15 in cell level and 24 in tissue level, far exceeding the clinically acceptable threshold of 2.0. Whatsm ore,t he strategy allowed the fluorescence discrimination of tumor tissues from inflammatory ones based on whether am arked fluorescence enhancement could be induced when treated with PSiR3 and b-Lap/ PSiR3 combination, respectively.