There is an urgent demand for on-site detection of biomarker, particularly in clinical diagnosis and therapeutics applications. Herein, we designed a convenient and sensitive fluorescence nanosensor for point-of-care determination of trypsin (TRY). The fluorescence intensity of gold nanoclusters (AuNCs) can be quenched by cytochrome c (Cyt c) via electron transfer mechanism. TRY specifically catalyzes the hydrolysis of Cyt c to produce small peptide fragments, inducing the significant fluorescence recovery. As a result, the AuNCs-based system processed a sensitive and selective response to TRY with the range 0.2-100 mu g mL^-1, accompanying a detection limit of 0.08 mu g mL^-1. Significantly, the sensing assay can be used to construct test strips for rapid and visual recognition of TRY. Combining with smartphone and ImageJ software, we further developed an image processing algorithm for quantitative detection of TRY with highly promising, which validated the potential point-of-care application.