The InAs/InGaAs dots-in-a-well (DWELL) structures were grown on both GaAs(311) B and (100) substrates by molecular beam epitaxy. Quantum dots (QDs) grown on GaAs(311) B substrate are of higher density and more uniform size distribution, yet QDs grown on GaAs(100) substrate demonstrate a bimodal size distribution. The growth mechanism of these surface morphologies was briefly discussed. We found that the photoluminescence (PL) linewidth of DWELL grown on GaAs(311) B substrate was much narrower than the linewidth of DWELL grown on GaAs(100), which suggests a promising advantage in many QD based devices. We also found the temperature had a stronger impact on the PL intensity of DWELL grown on GaAs(311) B, which was explained by the lower thermal active energy and higher density of interfacial point defects of DWELL grown on GaAs(311) B. These results provide people a rather comprehensive insight into the advantages and disadvantages of DWELL grown on GaAs(311) B substrates.