The invention provides a full-automatic glue sprayer and a glue spraying method. The full-automatic glue sprayer comprises a glue sprayer base, a cross beam, a glue injection barrel, a sliding mechanism, a heating mechanism, a detector and a sliding block controller. The heating mechanism is connected to the outer side face of the glue injection barrel and comprises a liquid inlet pipe, a spiral heating wire, a heat insulation barrel, a sealing plug and a liquid outlet pipe, the bottom of the glue injection barrel is connected with the inner bottom of the heat insulation barrel, the spiral heating wire is arranged in the heat insulation barrel and surrounds the outer surface of the glue injection barrel, the outer side face of the top of the heat insulation barrel communicates with the liquid inlet pipe, and the outer side face of the bottom of the heat insulation barrel communicates with the liquid outlet pipe. An injected sizing material is heated by a water bath method through watersolution heating, so that the heating uniformity is improved. Meanwhile, according to the full-automatic glue sprayer, the glue injection position of a glue spraying head is detected through a detection mechanism, when the glue spraying position is accurate, glue spraying is driven, and when the glue spraying position deviates, the glue spraying position is scanned again through controlling a laser component, and then the glue spraying route of the glue spraying head is rearranged through a main machine, so that the automatic glue spraying process is achieved.