A positron emission tomography method and a device with application adaptability. The method includes: step 1, scanning a tested object for obtaining initial activity information of the tested object; step 2, programming and adjusting a detector module based on the result of the initial scan to obtain a new system structure, and rapidly calibrating the new system structure; step 3, performing a scan with the new system structure for obtaining activity information of the tested object; step 4, analyzing the activity information of the tested object obtained at step 3. If quality of the activity information can satisfy requirements of the application, the scan is finished; otherwise programming and adjusting the detector module is repeated, rapid calibration is performed, and the activity information of the tested object is obtained again with the new system structure until the activity information satisfies requirements.