This study employs daily sea surface temperature (SST) data from OISST v2 during May–September from 1982 to 2022 and the three-dimensional connected-component method to identify marine heatwave events with continuous spatiotemporal evolution in the South China Sea (SCS). Based on the moving direction of their centroids, these events are classified into two types, naming northeastward-developing type and southwestward-developing type. Comparative analyses are conducted on the statistical characteristics of these two types of events. The research mainly obtains the following results. (1) The northeastward-developing events start from the ocean south of the Indo-China Peninsula, and subsequently expand northeastward under the background southwesterly monsoon. Then the warm SST anomaly expands to the entire basin in the mature stage, with the center remaining in the central SCS while the SST anomaly in the northern SCS keeping weaker. (2) The southwestward-developing events originate from the northeastern SCS. Due to the semi-enclosed ocean basin, the warm SST anomaly cannot expand northward; instead, it develops southwestward along the path of anomalous northeasterly winds, forming a strong northeast–southwest SST anomaly band in the mature stage. (3) The duration and cumulative affected area of the northeastward-developing events are significantly greater than the southwestward-developing events. The northeastward-developing events have an average duration of 61 days, compared to 37 days for the southwestward-developing events, and the longer duration leads to a larger cumulative affected area for the northeastward-developing events. (4) Anomalous atmospheric anticyclone is an important cause of both types of marine heatwave events. However, the northeastward-developing events are affected by a more persistent and significant anticyclone, which contributes to their longer duration.