The invention relates to an organic potassium fertilizer microbial agent. The organic potassium fertilizer microbial agent is characterized by being prepared by the following steps: after salt-tolerance colloid bacilli are activated on a nitrogen-free culture medium, the salt-tolerance colloid bacilli are transferred into a liquid culture medium and cultured, thalluses are collected by centrifugation, then kieselguhr, active carbon or plant ash with equivalent quantity is added as an adsorbent, and the mixture is dried at low temperature to obtain the organic potassium fertilizer strain agent. The invention also relates to a production method of biologic organic fertilizer. The organic potassium fertilizer microbial agent is prepared by combining a culture medium prepared by adopting seawater or bittern and the salt-tolerance colloid bacilli which are obtained by chemomorphosis or radialization mutagenesis and directed mutagenesis, can adapt to the seawater with a certain concentration and contain potassium bittern, the potassium content of the organic potassium fertilizer microbial agent is higher, and the organic potassium fertilizer microbial agent can be used as the biologic organic fertilizer, can be directly applied to common soil and salt alkali soil and can promote the absorption of plants to the soil and potassium in the microbial agent. The organic potassium fertilizer microbial agent also can be used as the organic fertilizer microbial agent and can produce organic potassium fertilizer and composite potassium fertilizer.