To study effects of fertilization depth of two slow-release fertilizers and cassava stem depth on the growth on the cassava variety NZ199, we set up 8 treatments, including two slow-release fertilizers(single-film small granules C1 and double-film small granules C2), four fertilization depths and cassava stem depths(the traditional cultivation with about 8 cm and the tested 10, 15, 20 cm, labelled as CK-8、C1-8、C2-8 etc). Agronomic traits, fresh root yield, tuberous depth, half width of cassava and fertilizer utilization rate were collected to index the growth. The results showed that the germination rate of two fertilizers with 15 cm depth were the highest, which were13.2% and 18.0% higher than 8 cm depth on the same fertilizers. At the root formation stage(after planted 79 d) and harvest stage, the plant height of C1-15 was significantly higher than that of C2-15, and stem diameter of C1-8 was significantly higher than that C2-8 at harvest stage, and C1-10 was significantly higher than that of C2-10. The single root weights, fresh root yields, starch yields and starch contents of C1-10 and C2-10 were the highest under C1 fertilizers and C2 fertilizers. The fresh root or starch yield of C1-10 were about 10% higher than those of C1-8, while those of C2-10 only increased slightly compared with C2-8 and the difference was no significant. The highest of the N, P, K utilization rate was 40.6%, 43.8%, 59.4% for C1-20, C2-8, C-10, respectively. In summary, the C1-10 was the optimal treatment in this field experiment, recommending to adopt 8-10 cm cassava stem and fertilization depth in cassava mechanized operation. In case of dry weather, the cassava stem depth could be appropriately increased.