A method for forming a contrast pulse sequence ultrasound image using a pulse width modulation scheme and an ultrasound system using the same are disclosed. The ultrasound system generates at least three kinds of mutually different pulses having a same amplitude, and sequentially transmits at least three kinds of transmission signals corresponding to the at least three kinds of mutually different pulses to an ultrasound transducer. The ultrasound transducer transmits at least three kinds of ultrasound signals to a target object by sequentially generating the at least three kinds of ultrasound signals based on the at least three kinds of transmission signals. The ultrasound transducer generates at least three kinds of reception signals by sequentially receiving at least three kinds of echo signals reflected from the target object. The ultrasound system forms a contrast pulse sequence ultrasound image by eliminating a linear component from the at least three kinds of reception signals.
