The invention relates to a coke car precise aligning judging method, which comprises the following steps of (1) giving the real-time measuring value S of an encoder to S0 at the moment that a code plate reading head is aligned with a code plate, wherein the S0 represents the encoder g value of the located position of the encoder card; (2) calculating the real-time position difference value of thecurrent position of the coke car and the current shown code plate position, namely the real time code plate deviation S1, wherein S1=S-S0; (3) performing the range limitation on the real time code plate deviation S1, wherein S1 is greater than or equal to -100mm but smaller than or equal to 100mm; when the value of the S1 is positioned in the limited range, regarding that the reading head furnacenumber is accurate and the code pushing can be performed; when the value of the S1 is beyond the limited range, regarding that the shown reading head furnace number has distortion and the code pushingcannot be performed. The method has the advantages that the accuracy and the reliability of the code car furnace number are greatly improved; the use rate of a four-vehicle linkage system is improved; the occurrence of red coke ground falling accidents and secondary safety accidents is avoided.