The invention discloses a PBF additive manufacturing-oriented method for determining the number of detection layers during single printing through using high-frequency ultrasonic on-line detection. The method includes the following steps that: S1, a sample is prepared; S2, the attenuation coefficient of the sample is tested; S3, the thickness of a simulated test block is determined; S4, the simulated test block is prepared; S5, a cross bore echo test is performed; S6, a data array A and a data array D are linearly fitted; S7, a detection rate is calculated; and S8, a corresponding defect depthis obtained according to the requirement of the value of the detection rate. According to the method of the invention, the attenuation coefficient is accurately calculated according to the sample; the maximum number of detection layers is accurately calculated according to the simulated test block with a cross bore under the premise of meeting the requirement of the detection rate, and therefore, printing efficiency can be maximized.