Abstract: Due to the global lack of fossil fuels, renewable energy sources like biomass and solar energy are being investigated in an effort to reduce carbon dioxide emissions while relieving the pressure on fossil fuels. Biomass has a special role in the manufacturing of fuel because it is a renewable energy source that contains carbon. Complex organic compounds, including alcohols, acids, and aldehydes, are present in the results of biomass pyrolysis and hydrolysis. The majority of these organic materials are of poor grade and cannot be used as fuel right once. Compared to hydrocarbon fuels, oxygenated fuels are more suitable for combustion in inner cylinders because of their ability to promote the depth of combustion, reduce the oxygen supply and the slag due to the incomplete combustion. The preparation of long chain oxygen-containing fuels from biomass not only has low raw materials, but also fully utilizes various lower quality oxygen-containing organic compounds after biomass depolymerization. In this article, common aldehydes, ketones, alcohols, ethers, and carboxylic acids formed from biomaterials are briefly categorized and introduced, along with the preparation processes and application domains. The methods for carbon chain elongation of these derivatives with oxygen by various chemical processes, such as aldehyde condensation, alkylation, polymerization, ketone production, Diels-Alder reaction, and reduction etherification, are also summarized in detail. The heating value can be raised and the material can be as closely matched to the primary constituents of existing fossil fuels as possible by lengthening the carbon chain of the reactants while maintaining a certain oxygen content. The aforementioned six pathways are divided into three groups in this article based on the features of various upgrading pathways, along with the conditions that each category must meet. This work serves as a guide for the development of biomass long-chain oxygen-containing fuels by thoroughly analyzing the synthesis pathways of long-chain oxygen-containing chemicals in the most recent biomass field.