The invention discloses a method for preparing a Fe film with a pyramid structure. The method comprises the steps of (1) selecting high-purity metallic iron target (the purity is 99.99%) as a sputtering target material and placing the target material into a magnetron sputtering chamber; (2) sequentially using acetone, alcohol and deionized water to perform ultrasonic cleaning to a monocrystalline silicon substrate and placing the processed monocrystalline silicon substrate into a magnetron sputtering chamber sample table; and (3) using argon gas as working gas as, adjusting sputtering pressure, exciting current, sputtering current and rotary rate of the sample table and performing sputtering for certain time to prepare the Fe film. Under the condition that direct current bias voltage is not exerted, the Fe film with the pyramid structure is prepared on the monocrystalline silicon substrate by appropriately controlling the sputtering pressure, the exciting current, the sputtering current and the like. The Fe film with the pyramid structure prepared on the monocrystalline silicon substrate is simple in preparation process and has wide industrialization prospect.