Three-line HF wide band antenna is a new type of short-wave communication antenna. In order to give full play to the performance of the antenna in omni-directional communication and directional communication, this paper first analyzes and calculates the radiation impedance and antenna pattern of three-line antenna at different work frequencies by using the method of moments, and obtains the curve of antenna directivity coefficient varying with working frequency, so as to effectively guide the frequency selection of antenna in omni-directional communication or directional communication; The simulation model of three-line antenna and typical ground objects is established by using electromagnetic simulation software FEKO, and the distortion law of antenna pattern under the influence of typical working frequency and different ground objects is obtained. It is concluded that the influence of height parameters on three-line antenna pattern is the most obvious, which provides a reference for engineering practice such as location selection and erection of three wire antenna.