Abstract: Cable formation testing is an important means of reservoir evaluation in Bohai Oilfield, but most directional exploration wells will add solid lubricant plastic balls into the drilling fluid due to engineering needs, and the inlet and outlet filter screen of the derivative subsequent cable formation testing instrument is blocked by plastic balls, which seriously affects the normal operation.In order to overcome the influence of plastic balls on the cable formation test, the main reason for the plastic balls to block the filter screen is analyzed. The idea that the inlet value and the outlet value should be closed before the instrument goes down the well, pump operation should not be carried out before sealing, and pumping should be carried out only after sealing is put forward. Combined with successful cases,the operation method of "No Sealing, No Opening; Shut Off, Before Release" is summarized. The popularization and application of this method can effectively overcome the influence of plastic ball on cable formation test, and the application effect is remarkable.