The invention discloses a ceramic tube type gas sensor and a preparation method thereof. The preparation method of the ceramic tube type gas sensor comprises the following steps: preparing a copper metal layer on the surface of the ceramic tube; and growing a copper oxide nano array on the surface of the copper metal layer to obtain the ceramic tube type gas sensor. According to the preparation method of the ceramic tube type gas sensor, the copper metal layer is prepared on the surface of the ceramic tube, and the copper oxide nano array grows on the surface of the copper metal layer, so thatthe purpose of preparing the copper oxide nano array on the surface of the ceramic tube to serve as the gas sensor is achieved, and the problems that the preparation method of the ceramic tube type gas sensor in the prior art is multiple and complicated in steps, high in preparation cost, easy to cause waste and not beneficial to gas response are solved.