A novel polymer of poly(diglycidyl maleate-co-stearyl methacrylate) (P(DGMA-co-SMA)) was synthesized by reaction between poly(maleic anhydride-co-stearyl methacrylate) (P(MA-co-SMA)) and epichlorohydrin. The self-assembly behavior of the resultant copolymer was investigated. It was found that the spheral aggregates could converse to nanorods after being aged for 2.5 days and nanolines composed of the nanorods were obtained after being aged for an additional 5.5 days. The mechanism of their self-assembly behavior and morphology conversion of self-assembly systems is discussed.