A heat-dissipating device having an air-guiding structure includes a heat-conducting seat, a fin assembly, at least one heat pipe for serially connecting to the fin assembly and the heat-conducting seat, and a fan assembly unit. The fin assembly is positioned above the heat-conducting seat and formed by arranging a plurality of heat-dissipating fins at intervals. As a result, airflow paths are formed between each heat-dissipating fin. The fan assembly unit is laterally provided at one side of the fin assembly. A space for lateral flow is formed between the heat-conducting seat and the fin assembly. The other side of the fin assembly is provided with an air-guiding member. The air-guiding member has a guiding space for laterally communicating with the space. The air blown by the fan assembly unit can pass through the space and is received by the air-guiding member. Then, the air flow is guided to the portions to be heat-dissipated by the air-guiding member.