The present invention proposes a method of obtaining a kind of bio-signal period and the system. The method after receiving a bio-signal value by comparing the size of the temporary value, which hold the one and The holding time is determined by the bio-signal value reaches the set time into one extreme value and Starting the cycle again to determine a next extreme value, and Through any one of the values to calculate the time between the extreme value and the next extreme value comprises the steps of obtaining a biological signal period. The present invention can be obtained a bio-signal period through the extreme value recognition algorithm, a simple, fast, efficient and there is a dominant high reliability, and low in the need for amplification, filtering and analog-digital conversion of the biological signal relative, and a data processing relatively easy and can significantly reduce the cost of the hardware.
