Abstract: Four pairs of rectangular block as longitudinal vortex generators（LVG） were mounted periodically in a narrow rectangular channel to investigate the fluid flow and convective heat transfer respectively in the narrow rectangular channel with LVG and without LVG.The experiments were performed with the channels oriented uprightly and uniform heat fluxes applied at the one side of the heating plate and single-phase water was used as test fluid.In these experimental investigations,both laminar regime and turbulent regime were under the thermo-hydraulic developing conditions,laminar-to-turbulent transition occurred in advance with the help of LV when Reynolds numbers vary between 310 and 4220.In laminar regime,LV causes heat transfer enhancement of about 100.9% and flow resistance increase of only 11.4%. And in turbulent regime,LV causes heat transfer enhancement of above 87.1% and flow resistance increase of 100.3%.As a result,LV can obviously enhance the heat transfer of single-phase water,and increase the flow resistance mildly.