Abstract: Hole cleaning Detecting is vitally important in the drilling of directional and extended-reach wells. Experimental and theoretical research has improved that hole cleaning detecting is efficient by monitoring annular pressure change. Traditional methods used to determine the change of the annular pressure through measuring static bottom hole pressure using sensor near the bit do not work well for this purpose because of its high cost and high failure in hole. This paper presents a new and economical method to calculate annulus pressure by measured standpipe pressure and the pressure drop of the bottom hole assemble calculated by some models. Examples are presented that represent actual field cases and demonstrate the advantages of using the advanced method compared to conventional methods of estimating hole cleaning in Bohai Oilfield.