The IR-2 Dual-Band Emissivity Measuring Instrument is widely used in the domestic normal temperature infrared technology research field at present. However, the problem is that the measured data has a greatly dispersion when using the IR-2 doing multiple measuring for the one same sample and the same group samples. The different flatness and the surface state of the samples might lead to the above phenomenon. The article discussed how the ceramic massive sample’s flatness and surface affect the measured values of the IR-2, and proposed the way to make the testing result more accurate and more stable. The research showed that the great deformation degree of the sample influences the accuracy; the ‘eight-divided equal angles’ test method and the treatment method what refers to take square root for the average value of the sum of the data’s square could realize less disperse among the measured values and more accurate in the case of the same group samples have different flatness state; the samples polished or not affect the value deeply.