The invention discloses a traditional Chinese medicine composition for treating arrhythmia and a preparation method thereof. The traditional Chinese medicine composition is prepared from lotus plumule, radix sophorae falvescentis, spikenard and salvia miltiorrhiza according to a certain weight ratio, and gen-seng, ophiopogon roots and shizandra also can be added to the traditional Chinese medicine composition. The traditional Chinese medicine composition can be prepared into any commonly used orally taking dosage forms, has the effects of clearing heat, calming down the heart, promoting the blood circulation, removing obstructions in channels, supplementing qi and nourishing yin and is used for treating patients with severe palpitation, irritability and insomnia, chest distress and breathlessness, tiredness and hypodynamia, intermittent pulse and premature beat caused by stagnant heat interties and insufficient Qiyin.