Objective Organisms are extremely responsive to the environments in which they live， and the traces they create are the result of interactions between organisms and their environment. To a certain extent， the traces reflect the properties of the depositional environment. Biological sedimentary structures are a powerful tool in understanding the ecology and depositional processes of modern coastal sedimentary environments. Methods The composition and distribution of modern biological traces in the tidal flat environments of the Pearl River Delta were studied by field observations and 3D reconstruction. Results The key understanding obtained by the study was that the distribution of organisms in the supratidal， intertidal and subtidal varies greatly， and the biological traces are mainly distributed in the intertidal zone. In the supratidal zone， mainly Ligia oceanica and Uca arcuata are present. The main traces are Uca arcuata level feeding traces， excretion traces， trackways， and intra-layer I-shaped dwelling burrows. Biological traces in the intertidal mud flat environment mainly include feeding， excretion， trackways and I-shaped dwelling burrows of Uca arcuata， crawling traces and Y-， U- and I-shaped dwelling burrows of Periophthalmus cantonensis， and trackways and I- and Y-shaped dwelling burrows of Orisarma dehaani. Biological traces in the mixed intertidal flat environment mainly include excretion traces and intra-layer I-， U-， and Y-shaped dwelling burrows of Perinereis aibuhitensis， Y-， U- and I-shaped dwelling burrows of Ligia oceanica， and crawling traces of Vittina coromandeliana and Neritina pulligera. Biological traces in the sandy intertidal environment include feeding and excretion traces of Ocypode cordimand and intra-layer I-shaped dwelling traces. The subtidal environment was not accessible for observation and no biological traces were found. Conclusions The study of modern intertidal biological traces in the Pearl River Delta supplements modern sedimentological data on tidal flat environments in the Pearl River Delta， and provides modern empirical evidence for palaeoichnology and palaeoenvironmental reconstruction.