A field experiment was conducted to investigate the phytate, phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), zinc (Zn) and manganese (Mn) contents during seed development and plant growth in soybean plants (Glycine max (L) Merr.). The amount of total P in plants increased with increasing plant dry weight. The seed P content increased sharply from anthesis, and the P distribution percentage in the seed reached 35% of the absorbed P at the full‐maturity stage. The P content in flowers was 5.62 g kg−1 dry matter, and that in the seed increased to 7.75 and 9.59 g kg−1 dry matter at 30 and 75 days after anthesis, respectively. The percentages of organic P and cellular P contents in the grain reached to 80–90% of the total P content at early immaturity stage, while it decreased with seed maturity. The percentage of phytic acid P in seeds to total P content was 68% at the full maturity stage. The phytate concentration negatively correlated with Ca, Mg, Zn, Mn and Fe concentrations in the seed; however, the total P concentrations in the seed correlated positively and the K concentration did not correlate with the phytate concentration. The Ca, Mg, Zn, Mn and Fe accumulated greatly at the early maturity stage of seeds; however, phytate accumulated with the increase in total P concentration with seed maturity.