Cephalopods are characterized by their short lifespan and semelparous strategy, in which the growth and development are highly correlated with the hatching seasons that highly influence the alternation of generations. Herein, based on statolith daily growth zones and back calculation of the hatching months, the size attainment of sexual mature Illex argentinus, an important world fishery squid species, was investigated and its relation to hatching months was analyzed using statistical methods. The results showed that:mature females were measured an average mantle length (ML) of (246.59±40.36) mm, an average age of (293.79±32.68) days, and a life history average growth rate of (0.84±0.11) mm/d; Mature males were measured a ML of (222.82±28.60) mm,a average age of (299.24±32.97) days and a life history aveage growth rate of (0.75±0.08) mm/d. Both females and males were estimated hatching months from March to August. As the hatching months progressed, both mature female and male I. argentinus showed a significant decrease in days of age, while they had a higher life history average growth rate. There was a significant relationship between maturity size attainment and life history average growth rate. The effects of hatching months on the attainment of maturity size highly consistent for both female and male I. argentinus, in which the earlier hatched individuals showed slower growth rate, while the later hatched ones grew faster to catch up the maturity size, possibly in order to cope with the coming spawning season. These evidences indicate the growth and development in I. argentinus are significantly related to hatching seasons, and individuals of different hatching months reach their sexual maturity size by adjusting their growth rate, in which later-hatched individuals likely appear to grow faster than earlier-hatched ones.