Thermogravimetric analyzer (TGA) under the influence of a static magnetic field and alternating gradient field magnetometer (AGFM) were applied to study the magnetic properties of electroplated film Co76Mo18Ni6. The film was amorphous before thermal annealing. Data from both magnetic measurements corroborate well with diffraction data. TGA is shown to supply vital information to help resolve the ambiguity in X-ray and electron diffraction data. Furthermore TGA can detect the subtle relaxation of amorphous alloy during a low temperature annealing before 250 degreesC. The relaxation is beyond the detection of current X-ray and electron diffraction technique.