An online capsule lottery system and method provides a lottery event in which a plurality of capsules are included in an online game. High-grade item contents having a high ability ranking in the online game is matched to at least one of the capsules, and lottery results are determined after capsules are extracted by the selection of the user. Even a player that has only recently begun playing the online game is given the opportunity to purchase a desired amount of the capsules and the chance to possess the high-grade item contents, thus enabling the player to easily become familiar with the online game. By adjusting winning odds in accordance with various ways of matching high-grade item contents with capsules, capsule purchase accumulation, and time of capsule purchase, the system and method prevent the balance of a game from being disrupted due to an indiscriminate distribution of items.