Sunshine duration is one of the observation elements in ground observatory. For a long time, sunshine duration is observed by Jordan sunshine recorders in China, which having poor precision, poor data comparability and low automatic level. With the development of modern techniques, some kinds of sunshine duration detectors and sensors are developed abroad, whereas there are few relative researches in China. In order to develop operational sunshine detector with independent intellectual property rights, current development and key techniques of sunshine detector based on direct radiation measurement are discussed. The sunshine detector based on direct radiation measurement has the widely prospect of application, radiation response of photoelectric sensor, design and encapsulation of radiation sensor, automatic solar tracking and structure optimization of equipment should be emphatically investigated, and the condition adaptability, stability and reliability should be promoted.