In order to solve the problems of wide linewidth of the vertical cavity surface emitting laser (VCSEL) used in traditional miniature and chip scale coherent population trapping (CPT) atomic clocks, a micro external cavity diode laser (ECDL) for CPT rubidium atomic clocks with a wavelength of 795 nm was designed using a self?developed laser chip and millimeter sized optical components. The laser has a size of less than 1 cm³ and features narrow linewidth and good direct modulation characteristics. Based on this ECDL, a miniature atomic clock with non?VCSEL light source has been achieved for the first time, with a short?term frequency stability of 3.70 × 10^-11@1 s and 1.35 × 10^-12@1 000 s. This is of great significance for the subsequent realization of high?performance miniature or even chip?scale atomic clock products.