The invention relates to an embedded-system-based asynchronous data receiving method, which belongs to the field of electronic equipment control. The method comprises the following steps that: a timing interval of a timer is set according to the baud rate of an upper computer; an external interrupt port of a system serves as a data receiver connected with the upper computer, and triggers the external interrupt of the system when receiving a data start bit from the upper computer, the system uses the external interrupt port as an ordinary input/output (I/O) port, and simultaneously the timer starts timing; the system performs sampling on the external interrupt port at a certain time interval, and stores obtained data; and when a data stop bit is obtained from the upper computer in the sampling, the system finishes the external interrupt, the timer stops timing, and the system stops using the external interrupt port as the ordinary I/O port. In the method, asynchronous data reception can be realized simply only by the external interrupt port and the timer.