The influences of the substrate as-heat-treated condition and the laser scanning speed on the nucleation position and the number of stray grains (SGs) in multi-traced deposition of DD5 single-crystal superalloys are studied. The formation mechanism of SGs under different conditions is also investigated. The results show that, when the laser scanning speed increases from 5 mm/s to 20 mm/s, the number of SGs decreases as a result of the columnar to equiaxed transition (CET) on the top of deposition traces. As for the solution-treated substrates, the number and the sizes of SGs at the bottom of the deposition traces are obviously smaller than those for the casted substrates. The overlapping among deposition traces does not create new SGs. When the solution-treated substrates are used and the laser scanning speed is 20 mm/s, an overlapping interface without SGs by multi-traced deposition can be achieved.