Quantitative real-time prediction model of workload that take into account influencing factors, task unit load, task conflict coefficient, and multi-task coefficient are proposed based on the operational tasks of pilots conducting flying activities in the cockpit environment. Selecting the normal pentagonal flight of the DA42 business jet as an example for prediction calculation, designing task scenarios, determining flight operation procedures, decomposing tasks, and calculating the real-time predicted flight workload values for different flight stages through a comprehensive calculation formula. In order to subjectively assess the flight workload under various flying stages, a validation experiment was carried out on the DA42 business jet flight simulator utilizing four subjective assessment scales: NASA-TLX, Bedford, Overall workload, and SWAT. The subjective evaluation values obtained were highly correlated with the workload values predicted by the prediction model. This verified the correctness and usability of the proposed model of workload proposed in this study.