The invention provides edible oil containing molecular markers as well as a preparation method and application thereof. The edible oil contains proanthocyanidins with concentration of 1-80mu g/ml. The edible oil can be used for conveniently and accurately detecting whether the edible oil is cooked and/or is subjected to heat recovery processing. A detection method comprises the following steps: (1) measuring the actual proanthocyanidin concentration (PT) and the actual anthocyanin concentration (AT) in an edible oil sample; (2) respectively comparing the actual proanthocyanidin concentration (PT) with the theoretical proanthocyanidin concentration (PE) and comparing the actual anthocyanin concentration (AT) with the theoretical anthocyanin concentration (AE) and respectively computing the ratio of the actual proanthocyanidin concentration (PT) to the actual anthocyanin concentration (AT) and the ratio of the theoretical proanthocyanidin concentration (PE) to the theoretical anthocyanin concentration (AE) to determine whether the edible oil is cooked and/or is subjected to heat recovery processing.