In the past two decades, an increasing amount of research has been conducted in nanoscale heat transfer.. Recently , researchers have considered the possibility of enhanced boiling heat transfer in nanofluids. Results reported in literatures are in conflict due to the dependence of experimental results upon many parameters such as the nanofluid type, heater material and specific test conditions, surfactant use, heater geometry, saturation pressure, and measurement equipments. In order to investigate on pool boiling in heat fluxes; thus some limited experimental data on boiling nanofluids over the flat plate has been reported. Also, previous results show that there are some conflicts. The comparison of the limited existing results of the pool boiling on the flat plate shows that research work on boiling heat transfer characteristics is still concentrations of nanoparticles. Experiments are carried out to investigate the effects of the nanoparticles’ concentration on pool boiling features, such as boiling curve, the CHF and boiling heat transfer coefficient. This study will also try to present some plausible explanations in results by analyzing the heater surface. heater has been studied experimentally. The maximum value of the surface (d=36mm) heat flux for all the boiling experiments was restricted to around 1,800 kW/m². Reduction in nucleate boiling heat transfer has been observed at four volume fraction of nanoparticles compare to pure water (for 0.1, 0.05, 0.02 and 0.002%.vol 40, 34, 23, 13% respectively). Results showed that the rate of heat transfer falls with solid concentration. Also enhancement in critical heat flux (CHF) has been observed (for 0.1, 0.05, 0.02, 0.002 and 0.001 %.vol. 47, 40, 30, 22, 17% respectively). The CHF enhancement increases with volume fraction of nanofluids. A thin layer of nanoparticle was seen on heater surface after boiling of nanofluids. Atomic force microscope (AFM) surface analyzing before and after boiling with nanofluids demonstrated that the surface roughness values changes. Roughness value after 0.02%vol nanofluids boiling on polished surface varies from 5nm to 376nm and for unpolished surface changes from 77nm to 197nm. Nanoparticle sedimentation on the heater surface during pool boiling causes to fill up nono-pores thus the number of nucleation sites and heat transfer rate decrease, consequently. In addition, nano-coating of heater surface owing to deposition of nanoparticle during nanofluids boiling, creates an excess conduction heat resistance between surface and working fluid, thus reduces heat transfer rate, too. However thin layer formed due to nanoparticle sedimentation on the surface, decreases drops contact angle on the surface and increases surface wettability that cause to increase in CHF.