In this work, high temperature solution-electrospun isotactic polypropylene (iPP) fiber and iPP/multiwalled carbon nanotube composite fiber are obtained. Compared with the iPP fiber, the composite fiber has a less grooved structure. After the electrospun fibers are embedded in an iPP matrix, both spherulites in the bulk and a layer of the transcrystallinity surrounding both the fibers are observed. However, there are no changes for the transcrystallinity in the composite fiber/iPP matrix even after melting and recrystallizing six times, indicating a super thermal stability and crystalline memory effect. Nevertheless, the crystalline memory effect of iPP fiber can be enhanced by annealing.