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We here report a monitor of the BL Lac object 1ES 1218+304 in both B- andR-bands by the GWAC-F60A telescope in eight nights, when it was triggerd to beat its highest X-ray flux in history by the VERITAS Observatory and Swiftfollow-ups. Both ANOVA and $\chi^2$-test enable us to clearly reveal anintra-day variability in optical wavelengths in seven out of the eight nights.A bluer-when-brighter chromatic relationship has been clearly identified infive out of the eight nights, which can be well explained by the shock-in-jetmodel. In addtion, a quasi-periodic oscilation phenomenon in both bands couldbe tentatively identified in the first night. A positive delay between the twobands has been revealed in three out of the eight nights, and a negative one inthe other nights. The identfied minimum time delay enables us to estimate the$M_{\mathrm{BH}}=2.8\times10^7 \rm M_{\odot}$that is invalid.

The intra-day Optical Monitoring of BL Lacerate Object 1ES 1218+304 at Its Highest X-ray Flux Level