The invention provides a non-phosphorus scale and corrosion inhibitor containing fulvic acid. The non-phosphorus scale and corrosion inhibitor containing fulvic acid is composed of a scale inhibition component, a corrosion inhibition component and deionized water. The scale inhibition component is composed of fulvic acid, a maleic acid-acrylic acid biopolymer and polyaspartic acid. The corrosion inhibition component is composed of zinc sulfate and polyoxyethylene naphthenic acid imidazoline. A preparation method of the non-phosphorus scale and corrosion inhibitor comprises the following steps: adding zinc sulfate into deionized water to obtain a mixture A; adding fulvic acid into the mixture A to obtain a mixture B; successively adding the maleic acid-acrylic acid biopolymer and polyaspartic acid into the mixture B to obtain a mixture C; and finally adding polyoxyethylene naphthenic acid imidazoline into the mixture C to obtain the non-phosphorus scale and corrosion inhibitor. The corrosion inhibitor is phosphorus-free, contains fulvic acid, has good corrosion inhibition property and scale inhibition property and is especially suitable for high-hardness and high-alkalinity water in North China.