The invention relates to the field of ecological environment monitoring and analysis, and in particular relates to a method for detecting the accumulation rate of shellfish cultured blue carbon in a sediment. The method for determining the accumulation rate of shellfish cultured blue carbon in the sediment comprises the steps that (1) m and n observation points are set in a shellfish culture zoneand an adjacent non-shellfish culture zone respectively; (2) sediment samples from the observation points are collected to construct a spectral model of the carbon content in the sediment; (3) the spectral data of the observation points are measured and substituted into the spectral model to calculate the carbon content of the sediment profile of the observation points; (4) the carbon content of the sediment profile of the observation points is converted into the carbon reserve of the observation points through a conversion coefficient t; and (5) the accumulation rate of cultured blue carbon in the sediment in a certain period of time is calculated through a formula. The method for determining the accumulation rate of shellfish cultured blue carbon in the sediment solves the difficulty ofemission reduction quantifying of culture sink, and facilitates scientific evaluation of the contribution of the culture carbon sink.