The invention provides a detection method of vital signs during sleeping. The detection method is based on a sleep detection device which comprises a piezoelectric thin film sensor, and the piezoelectric thin film sensor collects pressure signals when a person sleeps. The method includes following steps: performing power amplifying and filtering on the pressure signals; setting sampling frequency,and performing AD sampling on processed pressure signals; selecting a time period, and processing the pressure signals collected within the time period to serve as reference signals for judging whether a user has heart beat, respiration, snoring and body movement; dividing the pressure signals into four branches, namely heart beat signals, respiration signals, snoring signals and body motion signals; according to the heart beat signals, the respiration signals, the snoring signals and the body motion signals, respectively calculating heart beat data, respiration data, snoring data and body motion data; according to the heart beat data, the respiration data, the snoring data and the body motion data, acquiring the vital signals of the person.