Oyster mushroom is one of mushrooms that are cultivated and consumed a lot in Korea. P. ostreatus 'ASI 2504(Suhan)' is a preferable cultivar to mushroom farmers because it has a dark pileus and a thick stipe. But it is very sensitive to environmental conditions, so farmers demand an alternative cultivar of ‘Suhan’ continuously. To develop a new cultivar, parental strains ‘ASI 2504(Suhan)’ and ‘ASI 0665(Heuktari)’ were selected from P. ostreatus’s various collected strains according to morphological characteristics. P. ostreatus ‘Soltari’ was developed by the method of Di-Mono crossing between dikaryotic strain ‘Suhan’ and monokaryotic strain derived from ‘Heuktari’. Analysis of the mitochondrial genetic characteristics was performed for primary selection in 100 crossed strains. The mitochondrial DNA profile of ‘Soltari’ was same as that of ‘Heuktari’, when mitochondrial DNA primer MtPo1 was used. And a nuclear DNA profile of ‘Soltari’ was similar as those of the parental strains, ‘Suhan’ and ‘Heuktari’, when RAPD(Random Amplified Polymorphic DNA) primer URP 1, 3 were used. The optimum temperature for mycelial growth was 30°C for ‘Soltari’. ‘Soltari’ was appropriate for middle high temperature to grow, especially 13~18°C. Fruiting body production per bottle (1,100mL) was about 158.6g. When compared to the control strain ‘Suhan’, the stipe’s length and thickness of ‘Soltari’ were similar to those of ’Suhan’. But the pileus diameter of ‘Soltari’ was a little shorter than that of ‘Suhan’, the former was 42.72mm, while the latter was 51.33mm. And the pileus thickness of ‘Soltari’ and ‘Suhan’ were 18.18mm and 25.46mm, respectively. ‘Soltari’ was more resistant at high CO2 concentration than ‘Suhan’ and the color of pileus of ‘Soltari’ was kept dark gray at high temperature. Therefore, it is suggested that this new cultivar ‘Soltari’ be an alternative of ‘Suhan’ and contribute to energy saving effect in oyster mushroom farms.