  In a multi-wire proportional chamber detector(MWPC), the anode and signal
wires must maintain suitable tensions, which is very important for the
detector's stable and perfect performance. As a result, wire tension control
and measurement is essential in MWPC's construction. The thermal neutron
detector of multi-functional reflectometer at China Spallation Neutron Source
is designed using a high pressure $^{3}$He MWPC detector, and in the
construction of the detector, we developed a wire tension measurement system.
This system is accurate, portable and time-saving. With it, the wires' tension
on a anode wire plane has been tested, the measurement results show that the
wire tension control techniques used in detector manufacture is reliable.
