One of the most issues on exploiting effective parallelism is how to dynamically control parallel task derivation. In this paper,based on the ideal state of parallel tasks deriving, Eager Task Deriving (ETD)and Lazy Task Deriving(LDT) methods are analysed and discussed briefly, drawbacks of ETD and LTD are also presented. A practical Eager Lazy method is proposed for dynamically Deriving parallel Tasks (ELDT). The exprimental results have shown that ELDT can effectively control and increase the granularit