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Ultrathin flat metalenses have emerged as promising alternatives to conventional diffractive lenses, offering new possibil-ities for myriads of miniaturization and interfacial applications. Graphene-based materials can achieve both phase and amplitude modulations simultaneously at a single position due to the modification of the complex refractive index and thickness by laser conversion from graphene oxide into graphene like materials. In this work, we develop graphene ox-ide metalenses to precisely control phase and amplitude modulations and to achieve a holistic and systematic lens design based on a graphene-based material system. We experimentally validate our strategies via demonstrations of two graphene oxide metalenses: one with an ultra-long (～16λ) optical needle, and the other with axial multifocal spots, at the wavelength of 632.8 nm with a 200 nm thin film. Our proposed graphene oxide metalenses unfold unprecedented oppor-tunities for accurately designing graphene-based ultrathin integratable devices for broad applications.