The quasi-steady-state method in college physics experiment really needs four samples, and the main testing instruments are simple, so it can't do a good job of heat insulation and prevent heat loss. Only multiple samples can ensure one-dimensional heat flow, that is, a plane heat source is sandwiched between two samples and a temperature sensor is sandwiched outside the two samples. Even so, the measurement error is very huge. The truly engineering and standardized quasi-steady thermal conductivity tester can only use one sample, and is equipped with good heat insulation measures, with high measurement accuracy.