This paper conducted an experimental investigation on flow and heat transfer characteristics associated with the forced flow of de-ionized water in a periodical changeable cross-section micro-channel(PCMC) heat sink.The friction factor,Nusselt number,average temperature of heating film and thermal resistance of heat sink under different pump power were obtained.In comparison with traditional micro-channels with constant cross-section,the periodical changeable cross-section micro-channels could produce higher heat transfer coefficients and friction factors.