The external hydraulic casing running tool is used for casing running operation with the top drive  drilling  system.It  is  connected  with  the  top  drive  main  mandrel  or  the  compensator, and   exactly   control   the   makeup   torque   of  the   casing   by   top   drive   transmission.The hydraulic  structure  drive  slip  restoration  or  expansion  to  release  or  clamp  the  casing  to deliver  rotating  and  lifting  load  and  finish  makeup  and  lift  casing  and  rotate  running  in casing.The device uses a self-sealing cup to seal casing,and it can be filled with mud when running  in  the  casing,it  can  also  circulate  the  mud  in  time  when  the  casing  is  blocked,to reduce or avoid in complex accident occur,meanwhile it can test pressure for casing.