The present invention relates to a spirocyclic indolone polyethylene glycol carbonate compound, a composition thereof, a preparation method therefor, and a use thereof as an anticancer drug due to the antitumor activity thereof. The structural formula of the spirocyclic indolone polyethylene glycol carbonate compound is shown below. The compound has excellent tumor inhibitory activity, water solubility, low toxicity, and can be used for intravenous injection.