The utility model belongs to the technical field of monitoring of oil exploration and development logging pit shaft and evaluation technology equipment, especially, relate to a force measuring deviceis cut on line to drilling fluid. It discovers in time that drilling fluid rheology is unusual, combines the pit shaft monitoring and evaluatees hydraulics and rub and hinder the moment of torsion module, finally reaches and prevents the purpose of relevant risk in the pit. Include: sample filtering component, box shear force analysis appearance, power and terminating machine, sample filtering component includes filter, air powered pump and a sample section of thick bamboo, the filter links to each other with the medium inlet of air powered pump, the medium export of air powered pump links toeach other with the inlet of a sample section of thick bamboo, box shear force analysis appearance includes rotating electron shear force meter, the rotor of electron shear force meter dipes being surveyed in the drilling fluid of a sample section of thick bamboo, the torque sensor output of electron shear force meter links to each other with PLC, PLC links to each other with the terminating machine. The power is used for the power supply of electron shear force meter, PLC and terminating machine.