Recycled polypropylene (PP)/carbon nanotube (CNTs) composites with different CNTs fraction were prepared by the melting blend method. The effects of CNTs content on the thermal properties and mechanical properties were mainly investigated. The results show that the thermal degradation of the composites shifts towards higher temperatures as the concentration of CNTs is increased. With increasing CNTs content, tensile strength and elongation at break increase firstly and then decrease. When CNTs content is 3 %, tensile strength and elongation at break are 34.71 and 27.00, respectively. Moreover, a unique tensile rupture characteristic was found by SEM observations, which explained the critical broken theory of the PP/CNTs composites.