A coil assembly for a linear motor includes a coil unit which has multiple adjacently arranged coils, a base, and a resin encapsulated layer. The coils have two corresponding vertical action sides, a first non-action side, and a second non-action side. The coils further form multiple interlaced first bending sections on the first non-action side. Plural conducting wires disposed on the second non-action side could connect to an external cable on an end section of the coil unit. The base has a receiving slot thereon. The cross-section of the receiving slot corresponds in shape to that of the first bending sections for insertion of the coils. The resin encapsulated layer covering the coils and sealing the receiving slot of the base increases the contacting area between the coils and the inner wall of the receiving slot of the base to enhance the heat dissipation rate.