Abstarct: In nature, rivers can be divided in two categories: Sand and Gravel bed streams. The main difference is channel bed materials in gravel bed streams materials is typically poor sorted but in sandy streams the bed material is more uniform. More over due to flow characteristics streams can be classified to perennial and ephemeral streams. Perennial rivers which generally found in humid environments and convey water throughout the year, have low discharges and bed shear stress. As a result bed load transport in these streams is not very high. Existing coarser laxyer on the subsurface material is on of the most important features in perennial streams. This laxyer called armouring laxyer. Armoured laxyer protect bed-material from scouring. While ephemeral streams have commonly seen in arid and semiarid environments, discharge water infrequently during flood events. With a view to estimating bedload transport in gravel bed streams many equations have proposed but most of them make high errors and cannot be used in all rivers. In addition most researchers have used one diameter as indicator of bed materials. In this research a new relation has been proposed for estimating bedload transport in gravel bed streams. In this research a relation has been shown the average diameter for every minute as indicator of bed material. At the end new relation has been compared with other famous relations