Nowadays, many communication signals and radar signals coexist in the battlefield environment and civil life, and the spectrum resources are increasingly scarce. To prevent mutual interference between radar and electronic systems in the same frequency band, based on waveform design and diversity, this paper studies spectrum coexisting waveform design of radar to solve the spectrum congestion problem (SCP). First, we establish a mathematical model of spectrum coexistence waveform design on the idea of spectrum shaping. Then, we apply constant modulus constraint, peak-to-average (PAR) power ratio constraint and similarity constraint to the model and solve them respectively. For the constant modulus constraint model, we use alternating iteration method (AIM) and SHAPE algorithm to solve it. After converting the original model into a simpler equal form, we use KKT condition to successfully deal with the PAR problem and give a good solution to the similarity constraint problem. Finally, the numerical examples are presented to demonstrate the excellent performance of our models.