Abstract: To realize task scheduling and time management of workflow management system, avoid overflow while multitasks running in the workflow at the same time, and improve workflow’s efficiency, floating-delay is adopted to define colored timed Petri net. Overflows are avoided through controlling minimum time lags between tasks. Corresponding control strategies are implemented by the use of task monitor. Optimization aiming is the interval between each task is minimum. Temporal analysis and task scheduling are implemented for basic colored timed workflow nets, namely serial, parallel, conditional option and loop colored timed workflow net. Mathematic models of multitasks scheduling for basic colored timed workflow net are presented, and the formulae of calculating the whole workflows running time are given. At last an examine and approve workflow model built upon Colored timed Petri net is illustrated as an example to analyze and validate the methods discussed on multitasks scheduling.